In general, a large-sized transporter vehicle called a dump truck has a liftable vessel (loading platform) on a frame of a vehicle body, and carries and transports objects to be transported such as crushed stones or earth and sand in a state in which the objects to be transported are loaded in a large quantity on the vessel (for example, Japanese Patent Laid-Open No. 2001-105956 A and Japanese Patent Laid-Open No. 2006-347502 A).
A transporter vehicle of this type according to the prior art comprises an automotive vehicle body, a loading platform which is tiltably (liftably) provided on the vehicle body and on which the objects to be transported are loaded; a hoist cylinder which is telescopically provided between the loading platform and the vehicle body and extends at the time of dumping the objects to be transported from the loading platform so as to tilt the loading platform diagonally backward of the vehicle body; and control means for controlling a motion of the hoist cylinder.
This type of transporter vehicle self-travels to the transportation destination in a state of loading earth and sand or crushed stones in the loading platform and thereafter, extends the hoist cylinder to diagonally backward raise the loading platform. This raising operation dumps the earth and sand or the crushed stones to a cargo collection site along a tilting direction of the loading platform. At this time, since the loading platform is largely tilted backward of the vehicle body according to an extension operation of the hoist cylinder, the earth and sand or the crushed stones in the loading platform slide from a top surface (tilted surface) of the loading platform to be discharged (dumped) to an outside.
After such a dumping operation is completed, the hoist cylinder is contracted by a manual operation of an operation lever or the hoist cylinder is contracted by a self weight of the loading platform side. This operation causes the loading platform to bow down so as to gradually fall down to a position where the loading platform is seated on the vehicle body.